The present invention relates to digital signal processing apparatuses connected to each other for transmitting/receiving content having copyright.
If content is transmitted/received through a digital signal bus, video signals/audio signals, data, etc. can be transmitted/received without deterioration of quality, and this gives a large merit to users. Protection of copyright, however, causes a problem because there is no deterioration in quality. A technique for encrypting the content to be transmitted/received through a digital signal bus is described in NIKKEI Electronics, No. 712, Mar. 23, 1998, pp. 47-53. According to this technique, authentication is performed on transmission and reception side apparatuses so that the transmission/reception of content is enabled only between the apparatuses where authentication is established. The process protects copyrighted content from illegal copying.
Not only content but also information for controlling respective apparatuses can be transmitted through the aforementioned digital signal bus. Accordingly, one apparatus can control all the apparatuses connected to the one apparatus through a digital signal bus.
Although the use of the aforementioned technique makes it possible to protect the copyright of content, both authentication and encryption among apparatuses are so complex and the quantity of information to be processed is so large that a long time is required for processing. Furthermore, as the number of connected apparatuses increases, the quantity of information to be processed increases. Accordingly, there arises a problem in handling property. As described above, when content is to be transmitted/received through a digital signal bus, both achievement of handling property bearing comparison with that of conventional analog signals and protection of the copyright of the content without users' awareness become a problem to be solved.
Although the use of the aforementioned technique makes it possible for any one of the apparatuses to control all the apparatuses, there are numbers of handling ways for one purpose. Accordingly, there is a possibility that users hardly understand the handling ways.